There are currently a wide variety of different blade types used on a wide variety of different cutting implements. Depending upon the implement used and the duty cycle that it must endure, periodic sharpening is required. A sharpening system and process is often adapted to the particular type of blade used.
One major drawback in the art of sharpening blades is that there is a certain amount of deterioration of the blade caused by the sharpening process. Over time, this can either destroy or alter the blade's fundamental characteristics. Accordingly, the precision of the sharpening device and sharpening process, (as well as the duty cycle of the blade) become critical to the life of the blade.
One type of blade that is subject to intense duty cycles, and subsequently frequent sharpening programs, is found in shears/scissors, especially those used for cutting hair. There are three types of blade typically found in barber shears/scissors, as depicted in FIG. 11. These include the beveled edge, the hollow ground edge, and the convex edge. There are also a wide variety of different systems and techniques for sharpening such blades. A number of these are disclosed in the following U.S. Pat. Nos. 3,733,751 to Williams; 2,753,666 to Sasse; 1,832,968 to Armey; 1,806,234 to Boyd; 5,941,763 to Kaye; 7,465,220 to Wolff; 970,227 to Homan; 3,879,899 to Ribar; and 4,528,778 to Wolff. All of these patents are incorporated herein by reference.
Practice indicates that convex blades are preferred for scissors or shears, especially those used for cutting human hair. Because of the duty cycle for such shears/scissors, frequent sharpening is necessary. Unfortunately, the sharpening of convex blades, such as those preferred in barbering applications, is the most difficult to accomplish. This type of blade is especially vulnerable to degradation or changes in shape during the sharpening process.
Currently, a number of approaches to the sharpening of convex edges, such as those that are used in barber shears exist. The first of these is to maintain the convex edge along the length of the blade by rolling the edge on the outside of a grinding wheel. This technique requires that several passes be made, in which the angle to the sharpening wheel is changed for each pass. The result is usually a series of hollow ground cuts that look similar to a convex edge, but in reality, differs slightly (as indicated in the comparison of edges depicted in FIG. 11). Usually, the last pass on the outer-most cutting edge, results in a hollow ground edge. This undesirable result is very difficult to avoid.
There are conventional sharpening devices that use a flat disk and a clamp to carry out a process of rolling the blade against the flat disk to create a convex edge. However, this approach has a number of problems. Firstly, if the blade is not lifted at exactly the right time (within a millisecond of the precise time required) during the pass, a “micro-bevel” is placed on the outside of the cutting edge. This is a deviation from the true convex edge (as depicted in FIG. 11).
Another problem with conventional sharpening process for shears/scissors is that many scissor manufacturers have started to coat the outside of the blade with electro-plated metals to provide certain blade characteristics. Unfortunately, when conducting the conventional process of rolling the blade during sharpening, the plating can be moved or damaged, resulting in an unsightly finish on the scissors, as well resulting in a failure to obtain a true convex edge.
To complicate matters, such problems are often exaggerated by some scissor designs that include a changing angle from the back of the blade to the tip. This initial design is accomplished in the factory by uniformly sharpening the scissors blades in the manufacturing plant and then bending them to the final curve (which includes the varying edge angle along the length of the blade). The result of this particular design is that the sharpening process is rendered extremely difficult, especially in view of the need to not alter or damage the blade.
Currently, approximately 90% of the barber/beauty shear manufacturing industry production is directed to convex edges. Further, approximately of all barber/beauty shears or scissors are coated with a colored finish. In order to address such products, conventional sharpening systems have become quite complex, and very time consuming. For example, a conventional sharpening process for a convex edge can take as many as four or five abrasive wheel changes (and many passes) for each blade. Even with extreme care and expenditure of time, damage or unfavorable deformation of the blade can still take place with conventional systems.
Accordingly, a need exists for a sharpening system, especially a sharpening system for shears or scissors, that can quickly sharpen a convex blade along its entire length without damaging or deforming the blade from its desired shape, or cover. An improved sharpening system would also be relatively error free while conducting rapid sharpening of both convex and bevel edged shears.